Serum cholesterol binding reserve (SCBR) designates the amount of cholesterol which a serum specimen can solubilize in addition to its cholesterol content. Recent studies indicated that decreased SCBR may be a risk factor for the development of premature myocardial infarction, especially among hyperlipidemic individuals. Since premature myocardial infarction and hyperlipidemia are associated with diabetes mellitus, it is proposed to investigate whether SCBR is lower in the diabetics, by comparing SCBR values between diabetics and non-diabetic controls, between the juvenile-onset and maturity-onset diabetics, and to correlate SCBR values with other laboratory and clinical findings. The influences of sex, age, body weight, drug therapy and ethnic background on SCBR will be considered in these comparisons. The biochemical basis of any abnormality associated with diabetes will be explored. The overall objective is to determine whether decreased SCBR and diabetes mellitus are independent risk factors.